1. Field of the Invention
The present invention relates to an image display apparatus and a computer-readable image display program storage medium for displaying medical images obtained by photographing a subject.
2. Description of the Related Art
In medical fields, conventionally medical images obtained by photographing the insides of subject's bodies using X-ray photographic apparatuses, ultrasonic apparatuses, endoscope apparatuses and the like are widely used for diagnosis of disease conditions of subjects. When the medical images are used for diagnosis, the progress on disease of the subjects can be understood without doing external damage to the subjects. As a result, information necessary for determining therapeutic strategy can easily be obtained.
In addition to the X-ray photographic apparatuses and the endoscope apparatuses, CT (Computerized Tomography) apparatuses and MRI (Magnetic Resonance Imaging) apparatuses are increasingly installed in hospitals. The CT apparatuses photograph cross-section images of the subjects at respective cutting positions. The CT apparatuses and the MRI apparatuses can reduce pain given to the subjects at the time of test in comparison with the endoscope apparatuses whose optical probe is inserted into bodies, and can check accurate position and size of nidus three dimensionally using cross-section images. For this reason, in recent years, these apparatus are adopted in complete medical checkups or the like.
In general, medical images photographed at the time of tests are normally saved for respective subjects together with the medical charts or the like of the subjects. At the time of actual diagnosis, medical images photographed at different periods are arranged to be displayed on a monitor, and compared to read. This comparative reading easily enables checking of a change in a size of the nidus, and thus it is one of very useful methods for diagnosing a symptom and an effect of cure.
When the comparative reading is carried out by using cross-section images taken by the CT apparatuses and MRI apparatuses, for example, cross-section images on which the same nidus seems to be presented are selected from cross-section images taken in tests. Thereafter, the selected cross-section images are arranged to be displayed. However, there is a problem that a work for manually selecting desired cross section images from a number of cross-section images takes great effort and time.
In this regard, Japanese Patent Application Laid-Open No. 8-294485 discloses a technique which acquires cross-section image groups including cross-section images taken in some tests, specifies cross-section images whose cut positions are the same as one another from the cross-section image groups, relates the specified cross-section images to one another, and also relates cross-section images other than the specified cross-section images whose cut positions are the same to one another. According to the technique disclosed in Japanese Patent Application Laid-Open No. 8-294485, for example, a cross-section image presenting a nidus or the like is specified from the cross-section images taken in the first test, and a cross-section image whose cut position is considered to be the same as that on the specified cross-section image from cross-section images taken in the second test. Then, cross-section images other than these two cross-section images whose cut positions are the same are automatically selected, and are displayed on a display monitor. For this reason, the work and time required for manually selecting the cross-section images can be greatly saved.
However, it is very difficult to photograph a subject in the exactly same pose at different periods. Tilts of cross sections with respect to the subject may slightly shift due to twist of the body. In addition, for example, even if the subject is photographed by adjusting the positions of legs and head, positions in a body axis direction with respect to a chest region and an abdominal region generally shifts due to movements of internal organs according to breathing and vital activities. In such a state, when the subject is photographed with a slice width of about 5 mm and niduses imaged on one cross-section image in one cross-section image group, the niduses may be imaged separately on cross-section images in another cross-section image group, or one nidus may be imaged on different cross-section images whose cut positions are different. For this reason, even when the technique in Japanese Patent Application Laid-Open No. 8-294485 is used, there is a problem that a medical doctor needs to manually reselect cross-section images.